With the development of the society, more and more users are using liquid crystal displays (LCDs) to process social activities, and more particularly they are using 3D shutter LCD devices which fully satisfy the users' need to watch 3D movies. A 3D shutter LCD device displays signals of the left eye and the right eye by screens of different frames during use, so that the frequencies of the screens are frequently refreshed. When the signals of the left eye and the right eye are switched, the switching time interval is short, and the crosstalk could easily be produced.
In order to avoid the crosstalk of screens, a 3D shutter LCD device processes the over drive when changing the signals of the left eye and the right eye, so that the switching time interval of the signals of the left eye and the right eye is reduced to avoid the crosstalk.
Therefore, setting luminance signals of different grayscale switching screens of a 3D shutter LCD device (in the condition of luminance signals, the crosstalk can be prevented.) need to be carried out by measuring 256×256 luminance signals when switching (i.e. the grayscale of the left screen is fixed, and luminance signals of 256×256 right eye screens can be measured after switching; then, the grayscale of the left screen is switched, and luminance signals of 256×256 right eye screens can be measured after switching, until the grayscale of the left screen has been switched 256 times), or by measuring 64×64 luminance signals when switching, and then the measured result is processed by linear interpolation.
No matter what the methods adopted for measuring the luminance signals of 256×256 or 64×64 grayscales, the methods need to processed with a lot of measuring operations and arithmetic operations of luminance of grayscale, so that the efficiency of obtaining the luminance signals of different grayscale of LCD is lowered.
Therefore, it is necessary to provide a method and device for obtaining image signals in order to solve the problems of the prior art.